Five new genetic links to Alzheimer's have been uncovered, raising the prospect of future treatments to prevent the disease.

The discoveries mean a total of 10 genes are now known to play a role in late-onset Alzheimer's, the most common form of dementia.

Eradicating the effects of all of them would remove 60pc of the illness in the population.

Leading researcher Professor Julie Williams said it may one day be possible to identify those people most at risk of Alzheimer's and offer them preventative drug treatments.

However, this was not likely to become a reality for at least another 10 years.

"I can envisage in 10 to 15 years' time we may be taking a number of drugs to prevent the onset of Alzheimer's in the same way as we take statins now to prevent the onset of heart disease," said Prof Williams, from the Medical Research Council Centre for Neuropsychiatric Genetics and Genomics at the University of Cardiff.

An estimated 850,000 people are living with dementia in the UK and Ireland alone, 62pc of whom have Alzheimer's. The medical and social costs of Alzheimer's have been estimated at more than the financial burden of heart disease and cancer combined.

Alzheimer's is a largely genetic disease. Up to 79pc of a person's susceptibility to the condition is thought to be determined by genes, with environmental factors accounting for the remaining risk. In the 1990s scientists discovered a mutant form of the APOE gene that occurs in about 40pc of all people who develop Alzheimer's in old age.

Since then several other genetic variants linked to the disease have been identified.

The new research, published in the journal 'Nature Genetics', has focused attention on genes that affect the immune system, cholesterol processing and a cellular process that removes toxic protein from the brain.

Scientists on both sides of the Atlantic combined the results of four separate genetic studies involving almost 60,000 people worldwide.

Prof Williams said: "What's exciting is the genes we now know of -- the five new ones, plus those previously identified -- are clustering in patterns.

"So several genes are implicating the immune system, for example, and it's telling us there's something different about the immune system of people who go on to develop Alzheimer's disease.

Toxic

She said one of the most significant finds was the link with endocytosis -- a waste disposal process that allows cells in the brain to clear away toxic amyloid-beta protein. Sticky lumps of amyloid-beta in the brain are strongly implicated in Alzheimer's. "We now have four genes that implicate this very precise process and it offers a very big clue that this process is playing a strong role in the development of Alzheimer's disease," said Prof Williams.

The new genetic discoveries mean it may not be long before a blood test is developed which can reveal a person's level of Alzheimer's risk in middle age.

Prof Williams said there was a good chance of the ongoing research leading to drug treatments which counter the genetic effects.